For what it's worth, I e-mailed the author of the spreadsheet, Jose L. Jimenez, a couple of days ago and offered him free use of our calculator app builder Calcapp. This spreadsheet in particular works poorly on mobile devices, and would be more at home as an app (designed for comparatively small screens). I received an automated reply, informing me that he (understandably) doesn't have time to reply to the mountain of feedback he's been getting.

Anyway, the spreadsheet is released under the GPL. If you know more about this subject matter than I do, and you're willing to convert it into an app, get in touch with me and I'll make sure that we put your app on an unlimited, free plan.